Manometer type depth gauges employing a transparent capillary tube closed at one end are well known. While such gauges are simple in construction, having no moving parts, there are, nevertheless, several disadvantages associated with them. For example, because of the small size of the capillary tubes they have been difficult to read. Also, since the ambient water flows into the tubes, they must be cleaned on a regular basis to remove dirt and the like and to prevent the growth of algae within the capillary passageway.